1qxd

From Proteopedia

Revision as of 16:50, 12 November 2007

Structural Basis for the Potent Antisickling Effect of a Novel Class of 5-Membered Heterocyclic Aldehydic Compounds

Overview

Naturally occurring five-membered heterocyclic aldehydes, including, 5-hydroxymethyl-2-furfural, increase the oxygen affinity of hemoglobin, (Hb) and strongly inhibit the sickling of homozygous sickle red blood (SS), cells. X-ray studies of Hb complexed with these compounds indicate that, they form Schiff base adducts in a symmetrical fashion with the N-terminal, alphaVal1 nitrogens of Hb. Interestingly, two cocrystal types were, isolated during crystallization experiments with deoxygenated Hb, (deoxyHb): one crystal type was composed of the low-affinity or tense (T), state Hb quaternary structure; the other crystal type was composed of, high-affinity or relaxed state Hb (with a R2 quaternary structure). The R2, crystal appears to be formed as a result of the aldehydes binding to fully, or partially ligated Hb in the deoxyHb solution. Repeated attempts to, crystallize the compounds with liganded Hb failed, except on rare, occasions when very few R state crystals were obtained. Oxygen, equilibrium, high performance liquid chromatography (HPLC), antisickling, and X-ray studies suggest that the examined heterocyclic aldehydes may be, acting to prevent polymerization of sickle hemoglobin (HbS) by binding to, and stabilizing liganded Hb in the form of R2 and/or various relaxed state, Hbs, as well as binding to and destabilizing unliganded T state Hb. The, proposed mechanism may provide a general model for the antisickling, effects of aldehyde containing small molecules that bind to N-terminal, alphaVal1 nitrogens of Hb. The examined compounds also represent a new, class of potentially therapeutic agents for treating sickle cell disease, (SCD).

Disease

Known diseases associated with this structure: Erythremias, alpha- OMIM:[141800], Erythremias, beta- OMIM:[141900], Erythrocytosis OMIM:[141850], HPFH, deletion type OMIM:[141900], Heinz body anemia OMIM:[141850], Heinz body anemias, alpha- OMIM:[141800], Heinz body anemias, beta- OMIM:[141900], Hemoglobin H disease OMIM:[141850], Hypochromic microcytic anemia OMIM:[141850], Methemoglobinemias, alpha- OMIM:[141800], Methemoglobinemias, beta- OMIM:[141900], Sickle cell anemia OMIM:[141900], Thalassemia, alpha- OMIM:[141850], Thalassemia-beta, dominant inclusion-body OMIM:[141900], Thalassemias, alpha- OMIM:[141800], Thalassemias, beta- OMIM:[141900]

About this Structure

1QXD is a Protein complex structure of sequences from Homo sapiens with SO4, HEM and FU2 as ligands. Full crystallographic information is available from OCA.

Reference

Structural basis for the potent antisickling effect of a novel class of five-membered heterocyclic aldehydic compounds., Safo MK, Abdulmalik O, Danso-Danquah R, Burnett JC, Nokuri S, Joshi GS, Musayev FN, Asakura T, Abraham DJ, J Med Chem. 2004 Sep 9;47(19):4665-76. PMID:15341482

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